I have never used the product but Black Kow, according to its website,

The all-natural, organic way to improve native soils is by using Black Kow® composted cow manure. By mixing Black Kow® cow manure with your native soil before planting, you do 3 important things:

So is sounds like it is intended as a soil amendment, a soil improver/fertilizer if you will, to be mixed in with either garden soil or container potting mix.

Are these plants in a container in straight Black Kow? If so, then you may not get blooms/fruitset as it is simply too high in nitrogen for tomato plants. Adding additional fertilizers could only compound the problem. Tomatoes need phosphorus for blooms and fruits so I assume you could try adding a high phos (middle number) fert, either liquid or granular.

How old are the plants? How big? Can they still be transplanted to the garden or other containers?

Dave

Here is a link that might be useful: Black Kow

There are instructions on the Black Kow website that tells you how to use the bag of Black Kow like a planter...just slice it open and insert a tomato plant....It suggested adding some magnesium to the plant but I would think you will be fine since they are giving these instructions..

I'm not sure as to why your plants are acting like too much nitrogen. It may be that there is a bit of variation between batches and bags of the product. Or maybe you over did it with the fertilizer, if you did follow their instructions to add some.

I have had inconsistent results with the Black Kow bag method. Second year doing it. I followed the web site instructions and things worked out fine last year. This year I am doing the same but with more plants, all tomato this year. The inconsistency occurs during the initial growth phase. Many of my seedlings are yellowish and some have the purple tinge to the leaves. They seem to be working through though and are looking OK now. Some of them, however, are growing like crazy and have many flowers. The Celebrity hybrid did best last year and is looking the best this year.

If you have seen my other posts about my soil born disease problems, you would understand why I am excited about importing new soil each year. At the end of this season I will have about 10 used bags to incorporate into my flower beds. It's a win win for me. I am taking photos again this year and will post my results as I get the time.

The Black Kow bag method seem to work best when the bags are set on the ground, with mulch covering the plastic as a cooling insulation. Less temperature fluctuations and lower max root temps that way.

Good luck!

Vance